Drill bit



June 10, 1952 c. H. WEILAND DRILL BIT Filed Sept. 8, 1947 1 C/EZEZZUE Welland Patented June 10, 1952 s; armies;

DRILL BLT; qmxemelnd wgiland, Oshkosh, Wis., assignor to he B9B:iml'fi infi-;; mD I1X;:QShkQSlI W s-. corpemiiqn tfw sw 1 im ication September Q 1' 772;?21" aplaims (01. 145- 1 This inventionrelates to improvements inliiufi c nd. refers rparticularlye to. drill; bits. in-

tendedv fon useJin woods Thqsebskilled. in. thesart .are [familiar with the way drills, or drill: bits heretoforeiavailableiiburnf when iisedin, har.d..-wood,- andrzwith -.'the resulting glaged, blfiC-k', surfaces. of the. drilled. zholee which makesi tt ifficult to secure. a goodlzgluetjoint,

wllfieathe holetreceives a dowel pin. The exces-i the. life .of its cutting :edge.

hese obiect onsiare specially-w n ticeable :in; he drills-em oyed,intm rt sing machines wh r the actuatdrill; or: rbitjjoperates :ina square-hole; qws c is over making it diflicult to securea gqodigluerjoint etween h emert s nd. tenonr lt rvis therefore an obi ect Of 1 this; invention to In thi s i case. .the hollow v.wzhisel, 1- as well as sthe actuali drill bitsafburnsi: 50413113111. the .1 suriace oi the mqrtise cut intotheworkzis glazed;

used in a l'i d;woodpnequivalent,materialrandl elsh heref re. ercpmesemet objections 1111-, e ent i drill. it -p l t ei a te With the above and other objects in:Viewwhich:

ller l n orfionof .a drill. bit constructed inaccordance with ,this invention;

Figure 1a is a similar view showing the old conventionalbrad point wood bit-which this invention supersedes;

Figure 2 is an end view of the bit shown in Figure 1;

Figure 2a is an end view of the conventional bit shown in Figure la;

Figures 3 to 5 inclusive are cross-sectional 4 views through Figure l on the planes of the lines 33 to 5-5 inclusive;

Figures 3a to 5a are similar cross-sectional views taken on the same planes but through Figure 1a;

Figure 6 is aidetailisectional view tak'emthrough; Figurei l ion the pla'ineiofvrthe.liner-6e45 Figure 6a is aasimi-lanwiewlbut*taken omithe plane .of the-line l fiafifiatofifigure 1 1a;

Figure .7 is aside View of .a portiomofi-a:mortiser;- bit :to ;:illus-trate, the application-of this invention; thereto; and

Figure 8 ris .-a bottom.-vie w .of the :mortiserz; bit shownlin Figuree'h Referringnow. particularly -to. .the accompany ingldrawi-ng thenumeral' l flidesignatesi the shank; Ofia :drill'bi-t which; asgsacustomary; hQSJODDOSitBL' muately :lacttomedzfiutes il l extendi-ng-shelically: backfire-m :its cutting-rend cl 2:;

In -vie.wt;of; the.:di:fiicu1ty .inportraying the sin-r. n ioaicomparable viewshavebeenshowniuuse matin both the .snewa-andpthe .oIdrQQnStructi'cinn and -the, 1numeralsi; here;;used-;;wil1: be applied .-.to:; bitl; crnew-l-zandeold ;censtructionszinsofan as posse- 51 e.

K Q 5m 3 .aiof:itherdrillxdirectly r'baokigof fits a-d ne ed e ;I A is, relievedyithatzi-sntis otsliehtlm ma er zd ami tfirg hazmthe edgexportion: 4: and

' mention-theeextent: of zthisxrelief-rfis deast: :subst tiahportion oirthw A im-fi s uttln wendeav, Thelglereera'tdi tinction, ever, z e weentthe fiqnstriict-ionrzofix; ler-inv ntion: nde onventionab idril'lgibits z lies mt eiactthatlthel a 'onheeleportionroi each': t-t e we t n sedees 5| 5 aground sewawsmthat he l; th cknessebetweenl theme-tee: H Zgmdr-L' ally 1 d:lmiiorml a ncreasesfrom; its pcuttingir edg ith th lladient f-athenincreaseso smali;

th sgpqintais backflqmzthfi,cuttingtedgesri s hi lyrg eaterzthen:the :diameter; of:

relief or clearance for the chips cut during the action of the drill is far greater than that which obtains in the conventional construction wherein the heel l6 of each of the cutting edges is a flat surface disposed at approximately 60 to the axis of the bit as shown in Figure 6a.

Another feature of this invention resides in the fact that the cutting edges l5 at the bottom of the drill form concave curves with their adjacent t l1 wa l-50h; nessubet-wmn the routes: sa: l ii e ched-r; rra a s ance; r approximately:

:the planer.- "represents the -point-iof'ifulldwallgthicknessia Iirwiew ;;Of .fithisn structural;;.'relationship,- :Lthqrends joined by a convexly curved central point I1, and that the cutting edges l5 extend across the point I! to form one continuous ogee curve when viewed from the bottom as shown in Figure 2. By virtue of this specific shape of the cutting edges the grain of the wood being cut invariably forms a chord to the cutting edges. As a result the chips are broken up into small pieces resembling sawdust as distinguished from the flat shaving-like chips produced by the conventional drill bit wherein the cutting edges l5 are straight and extend substantially radially from a diamond point IT to outer circle inscribing edges I8.

It has not been determined why the new construction produces the improved results achieved thereby but by test and actual working conditions it has been demonstrated that the drill of this invention operates satisfactorily in the hardest wood without the slightest sign of burning, whereas the conventional drill such as shown in Figure 1a becomes discolored and burns in a very few operations.

Moreover the holes drilled with the bit of this,

invention are clean and unglazed while those formed with the conventional bit are glazed over with a black glassy surface.

This invention is particularly advantageous when applied to mortisers as shown in Figures '7 and 8. In this case the drill is made in the same way as described, that is, the heel portion l9 back of the cutting edges 20 is relieved sufficiently to provide the gradually and uniformly increasing wall thickness between the flutes 2i hereinbefore described. The specific shape of the bit and more particularly the pitch and size of its flutes 22, however, is different from that of the conventional wood drill, being steeper and larger so as to afford greater clearance; and the entire bit operates within a hollow chisel 23.

It has been found that by grinding the cutting end of the drill so that its tip 24 is slightly off center (see Figure 8) improved results are obtained for, as a result of this eccentricity, the cutting end of the bit vibrates slightly within the chisel which facilitates cleaning out the stock from the corners of the square out.

From the foregoing description taken in connection with the accompanying drawing, it will be apparent to those skilled in the art that this invention provides a substantial improvement in drill bits of the type designed primarily for the use in wood and that by eliminating the burning of the bit and the wood the bit has a longer useful life and the surface of the drilled hole is better suited for gluing.

What I claim as my invention is:

1. A drill bit characterized by diametrically opposite helically extending grooves gradually increasing in depth near and toward the cutting end of the bit with the bottoms of the flutes intersecting substantially along a longitudinal plane containing the axis of the bit to define the cutting edges of the bit, said cutting edges forming in effect one continuous edge of compound curvature lying along said plane and when viewed endwise of the bit, comprising equally but 0ppositely curved outer portions tangent to opposite sides of said plane and a central portion of substantially slight ogee curvature joining said curved outer portions, said central portion occupying substantially the center one-third of the diameter of the bit and providing an axially projecting point having a rounded profile at its extremity, and said outer portions having identical deeply concave curvature with their inner edge portions merging smoothly with the side edges of said point when the bit is viewed from the side at right angles to said plane.

2. A drill bit characterized by diametrically opposite helically extending grooves gradually increasing in depth and decreasing in curvature near and toward the cutting end of the bit with the bottoms of said flutes intersecting to define opposite outer concave cutting edges tangent to opposite sides of a longitudinal plane containing the axis of the bit when viewed endwise of the bit, but deeply concave and tangent to the same side of a radial plane of the bit when viewed from the side at right angles to said longitudinal plane, and to define a central portion having ogee curvature along but crossing said longitudinal plane at the axis of the bit, said central portion of ogee curvature joining the inner ends of said concave cutting edges and when viewed endwise of the bit producing in effect a single continuous undulatory edge of relatively shallow curvatures across the diameter of the bit in which the ogee portion comprises substantially the center one-third of the diameter of the bit, and said central portion providing a smooth surfaced forwardly projecting point rounded in profile at its extremity when viewed from the side at right angles to said longitudinal plane.

3. The drill bit set forth in claim 2 wherein the said gradual increase in depth and decrease in curvature of the flutes toward the cutting end of the bit begins substantially at a point of full wall thickness between the flutes spaced from said end of the bit a distance at least equal to the diameter of the bit.

CLARENCE H. WEILAND.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 270,977 Payne Jan. 23, 1883 306,907 Dimitt Oct. 21, 1884 374,432 Simmons Dec. 6, 1887 404,197 Irwin May 28, 1889 528,725 Hussey Nov. 6, 1894 1,538,680 Boggio May 19, 1925 2,215,939 Shaw Sept. 24, 1940 2,230,645 Jones Feb. 4, 1941 FOREIGN PATENTS Number Country Date 364,750 Great Britain Jan. 14, 1932 

